MECHANICAL STRENGTH AND REMOVAL OF A PROTECTIVE IRON CARBONATE LAYER FORMED ON MILD STEEL IN CO2 CORROSION

It has been debated in the past whether, in turbulent flow, the hydrodynamic wall-shear stress can mechanically remove or damage a protective iron carbonate layer formed on mild steel in a CO₂ corrosion environment.  In this study, the mechanical strength of the iron carbonate layer was measured by a tensile machine. It was shown that the adhesion strength between the iron carbonate layer and the steel substrate is in excess of 10 MPa, which is many orders of magnitude larger than the typical wall-shear stress found in turbulent flow. Experiments conducted in a small scale single-phase flow loop confirmed that the iron carbonate layer could not be removed mechanically.